1. Field
The present invention relates to a wireless communication system that uses a multiple-input multiple-output (MIMO) antenna.
2. Discussion of the Background
As communication systems have developed, various wireless terminals have been utilized by consumers, such as companies and individuals.
A current mobile communication system, for example, 3GPP, Long Term Evolution (LTE), LTE-Advanced (LTE-A), and the like, may be a high capacity communication system capable of transmitting and receiving various data such as image data, wireless data, and the like, beyond providing a sound-based service. Accordingly, there is a desire for a technology that transmits high capacity data, which is comparable with a wired communication network. Also, the system is required to include an appropriate error detection scheme that increases transmission efficiency of the system so as to improve performance of the system.
A communication system based on a multiple-input multiple-output (MIMO) antenna is used in both a transmitting end and a receiving end. This has a structure in which a single UE (SU) or multiple UEs may receive/transmit a signal from/to a single base station (BS) and the like.
The system using the MIMO scheme may recognize a channel status based on various reference signals and the like, and may feed back the recognized channel status to a transmitting end (another device).
That is, when a single UE is assigned with a plurality of downlink (DL) physical channels, the UE may feed back channel status information associated with each of the physical channels to a BS so as to adaptively optimize the system. To achieve the above, signals, such as a channel status index-reference signal (CSI-RS), a channel quality indicator (CQI), and a precoding matrix index (PMI), may be utilized, and the BS may perform channel scheduling based on information associated with a channel status.